1. Field of the Invention
The present invention relates to a brushless rotary electric machine to be mounted in a vehicle as, for example, a brushless AC generator.
2. Description of the Related Art
Conventionally, the following AC generator for an automobile is known. The AC generator includes a case, a stator, a shaft, a rotor, and a cooling fan. The case includes a pair of brackets, i.e., a first bracket and a second bracket, which are opposed to each other. The stator is fixed to the case. Two ends of the shaft are rotatably supported respectively by the first bracket and the second bracket through an intermediation of bearings. The rotor is provided to the shaft. The cooling fan is fixed to the shaft. The rotor includes a magnetic-pole core fixed to the shaft, a cylindrical exciting core fixed to the first bracket while being inserted into the magnetic-pole core, and an exiting coil obtained by winding a conductor around a minor-diameter portion of the exciting core (for example, see JP 57-16559 A (FIG. 1)).
In the above-mentioned AC generator for the automobile, vent holes are formed through the rear bracket at positions so as to face a diode and a regulator. Therefore, cooling air generated by the rotation of the cooling fan passes through the diode and the regulator. After that, the cooling air reaches the exciting core and the exciting coil through the vent holes. Therefore, there are the following problems.
A. After cooling the diode and the regulator, the cooling air cools the exciting core and the exiting coil. Therefore, the exciting core and the exciting coil are cooled with the warmed cooling air. Therefore, cooling performance for the exiting core and the exciting coil is low.
B. There is no structure in an internal space after the cooling air passes through the vent holes, and hence the cooling air is disadvantageously diffused in the internal space. The exciting core and the exciting coil are cooled by the diffused cooling air, and hence the cooling performance for the exciting core and the exciting coil is low.